/*
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
 *
 * Copyright (c) 2008-2011, Salzburg Research. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 * - Redistributions of source code must retain the above copyright notice,
 * this list of conditions and the following disclaimer.
 * - Redistributions in binary form must reproduce the above copyright notice,
 * this list of conditions and the following disclaimer in the documentation
 * and/or other materials provided with the distribution.
 * - Neither the name of the LMF library client Project nor the names of its contributors
 * may be used to endorse or promote products derived from this software
 * without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 *
 * Contributor(s):
 * Stephanie Stroka
 *
 * File Info:
 * User: Stephanie Stroka
 * Date: 2011/08/19
 * Time: 18:04
 *
 * Project: lmflib
 */

package kiwi.facading.services;

import kiwi.facading.api.FacadingService;
import kiwi.facading.model.annotations.RDFFilter;
import kiwi.facading.model.annotations.RDFType;
import kiwi.facading.model.KiWiFacade;
import kiwi.facading.model.resources.KiWiResource;
import kiwi.facading.model.resources.KiWiUriResource;
import kiwi.facading.utils.FacadeUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.lang.reflect.Proxy;
import java.util.Collection;
import java.util.LinkedList;

/**
 * Offers methods for loading and proxying KiWiFacades. A KiWi Facade is an interface that defines a Java
 * object with convenient Java methods around a KiWiResource and makes it possible to use RDF properties like
 * Java Bean properties from inside Java.
 * <p/>
 * The facading service is used by many other services, e.g. ContentItemService and TaggingService, to provide
 * access on a higher level than raw RDF resources.
 *
 *
 * <p/>
 * User: sschaffe
 */
public class FacadingServiceImpl implements FacadingService {

    private Logger log = LoggerFactory.getLogger(this.getClass());

    private ResourceServiceImpl resourceService;

    public FacadingServiceImpl() {
        resourceService = new ResourceServiceImpl();    
    }

    /**
     * Create an instance of C that facades the resource given as argument using the @RDF annotations provided
     * to the getter or setter methods of Cto map to properties of the resource in the triple store.
     *
     * @param r    the resource to facade
     * @param type the facade type as a class
     * @param <C>  the facade type as a generic parameter
     * @return
     */
    @Override
    public <C extends KiWiFacade> C createFacade(KiWiResource r, Class<C> type) {
        if(r == null) {
            return null;
        } else if(type.isInterface()) {
            // if the interface is a KiWiFacade, we execute the query and then
            // create an invocation handler for each result to create proxy objects
            if(FacadeUtils.isKiWiFacade(type)) {
                // support @RDFType annotation in facade
                if(FacadeUtils.isFacadeAnnotationPresent(type,RDFType.class)) {
                    String[]        a_type = FacadeUtils.getFacadeAnnotation(type,RDFType.class).value();
                    for(String s_type : a_type) {
                        KiWiUriResource r_type = resourceService.createUriResource(s_type);
                        resourceService.addType(r,r_type);
                    }
                }

                KiWiInvocationHandler handler = new KiWiInvocationHandler(r,this, resourceService);
                  C entity =
                      (C) Proxy.newProxyInstance(type.getClassLoader(),
                              new Class[]{type},
                              handler);
                  return entity;
            } else {
                throw new IllegalArgumentException("interface passed as parameter is not a KiWi Facade");
            }
        } else {
            throw new IllegalArgumentException("interface passed as parameter is not a KiWi Facade ("+ type.getCanonicalName() +")");
        }
    }

    /**
     * Create a collection of instances of C that facade the resources given in the collection passed as argument.
     * The facade uses the @RDF annotations provided to the getter or setter methods of C. The returned collection
     * is of the same kind as the passed collection.
     *
     * @param list the collection containing the resources to facade
     * @param type the facade type as a class
     * @param <C>  the facade type as a generic parameter
     * @return
     */
    @Override
    public <C extends KiWiFacade> Collection<C> createFacade(Collection<KiWiResource> list, Class<C> type) {
        log.debug("createFacadeList: creating {} facade over {} content items",type.getName(),list.size());
        LinkedList<C> result = new LinkedList<C>();
        if(type.isAnnotationPresent(RDFFilter.class)) {
            // if the RDFType annotation is present, filter out content items that are of the wrong type
            LinkedList<KiWiUriResource> acceptable_types = new LinkedList<KiWiUriResource>();
            if(FacadeUtils.isFacadeAnnotationPresent(type,RDFFilter.class)) {
                String[]        a_type = FacadeUtils.getFacadeAnnotation(type,RDFFilter.class).value();
                for(String s_type : a_type) {
                    KiWiUriResource r_type = resourceService.createUriResource(s_type);
                    acceptable_types.add(r_type);
                }
            }

            // add facades for all content items to the result list
            for(KiWiResource item : list) {
                boolean accept = acceptable_types.size() == 0; // true for empty filter
                for(KiWiUriResource rdf_type : acceptable_types) {
                    if(resourceService.hasType(item,rdf_type)) {
                        accept = true;
                        log.debug("accepting resource #0 because type matches (#1)",item.getKiwiIdentifier(),rdf_type.getKiwiIdentifier());
                        if(log.isDebugEnabled()) {
                            for(KiWiResource _type : resourceService.getTypes(item) ) {
                                log.debug("type: #0",_type.getKiwiIdentifier());
                            }
                        }
                        break;
                    }
                }
                if(accept) {
                    result.add(createFacade(item,type));
                }
            }
            log.debug("createFacadeList: filtered #0 content items because they did not match the necessary criteria",list.size()-result.size());
        } else {
            // add facades for all content items to the result list
            for(KiWiResource item : list) {
                result.add(createFacade(item,type));
            }
        }
        return result;
    }

    /**
     * Create an instance of C that facades the resource identified by the uri given as argument, using the @RDF
     * annotations provided to the getter or setter methods of C to map to properties of the resource in the triple
     * store.
     *
     * @param uri  the uri of the resource to facade
     * @param type the facade type as a class
     * @param <C>  the facade type as a generic parameter
     * @return
     */
    @Override
    public <C extends KiWiFacade> C createFacade(String uri, Class<C> type) {
        return createFacade(resourceService.createUriResource(uri), type);
    }
}
